Microwave Synthesis of CdTe/TGA Quantum Dots and Their Thermodynamic Interaction with Bovine Serum Albumin

The thioglycollic acid (TGA) as a capping agent, CdTe/TGA quantum dots (QDs) with excellent properties were synthesized under microwave irradiation. The TGA/Cd/Te molar ratios, reaction time, temperature and pH are the crucial factors for properties of QDs. The QDs were characterized by UV-vis absorption and fluorescence spectra, transmission electron microscopy and Fourier transform infrared spectroscopy. The experimental results show that when the pH value is 11.5 and molar ratio of TGA:Cd:Te is 1.2:1:0.4 at 100 degrees C heating for 15 min, the resulted QDs exhibit a high fluorescence quantum yield of 78%. The fluorescence full width at half maximum (FHMW) of QDs is around 23 nm. The products are spherical with average size of 3-5 nm. There is a strong coordination effect between TGA and Cd2+. Moreover, the results of interaction between as-made QDs and bovine serum albumin (BSA) suggest that the QDs-BSA binding reaction is a static quenching. The negative values of free energy (Delta G<0) suggest that the binding process is spontaneous, Delta H<0 and Delta S<0 show that hydrogen bonds and van der Waals interactions play a major role in the binding reaction between QDs and BSA.